Future Mars astronauts may be tired, bored and moody

Future astronauts going to Mars could have trouble sleeping,
become lethargic, and have problems with mental tasks over the
course of a long mission.

That is one takeaway from the Mars500
experiment, an international test run by the Russian Academy of
Science in conjunction with the European and Chinese space
agencies. The experiment placed a six-man crew in a simulated spaceship en route to Mars for 520 consecutive
days during 2010 and 2011.

"Our major finding was that there were really large individual
differences with how the crew responded to the isolation," said
psychiatrist Mathias
Basner of the University of Pennsylvania School of
Medicine, who helped run the sleep experiment, which appeared 7
January in the Proceedings
of the National Academy of Sciences. "Four of them showed
at least one issue that could have exploded or led to a severe
adverse effect during a Mars mission."

Similar experiments in the past have studied the psychology of
isolated groups, such as crews overwintering in Antarctica, but
Mars500 was the first detailed simulation of circumstances that
could arise during a manned Mars venture.

While two of the participants fared very well under this
prolonged period of isolation, all members reacted fairly
differently. Most crewmembers stayed on a 24-hour sleep cycle
schedule, but one fell into a 25-hour day. "He became
disconnected," said Basner, adding that about 20 percent of the
time he was the only crewmember awake or the only one asleep.

"If you have people awake when others are sleeping, that doesn't
bode well for crew dynamics and cohesion," said biomedical
researcher Lauren B. Leveton, who studies behavioural health and
performance at Nasa's Johnson Space Center and who was not involved
with the research. Such detachment would likely have to be
counteracted in a real deep-space mission, she added.

Another interesting observation from the experiment was that all
the volunteers slept much more then usual. Basner chalks this up to
the fact that for much of the mission, they had ample time to do
nothing. Most people in modern society, he said, have sleep
deficits they never make up because our lifestyles encourage
constant work activity and caffeine use. Given enough sleep, most
of the participants actually saw increased cognitive performance
overall.

The other side of this was that crewmembers often succumbed to
boredom and monotony. There were only so many times they could
play Guitar Hero. The volunteers became sedentary,
reduced their movement while awake, and spent more time sleeping
and resting.

But even here there was considerable difference. One member of
the study began sleeping for shorter and shorter intervals, which
caused his cognitive abilities to suffer. Another had issues with
mood and depression.

"There's a lot of value in this type of research, it's an
excellent study," said Leveton. Future work could help elucidate
particular factors affecting the crewmembers by varying
different conditions, such as the amount of privacy or social
interaction times, she said.

But other researchers would have liked the simulation to address
how the Martian day might affect crewmembers. Since a day on Mars
is slightly longer than one on Earth (a Mars day is 24.65 hours),
astronauts on the surface on Mars might have trouble with their
circadian rhythm getting out of sync with actual day/night cycles.
The effects from the current study are "likely to be much worse
during a real Mars mission when individuals might be asked to live
on a Martian day if they live on Mars," wrote
neuroscientist Steven W.
Lockley of Harvard Medical School, who was not involved in
the research, in an email to Wired.com.

Though nothing serious happened to the members of Mars500, it
shows some of the major issues in trying to screen possible
participants in a real long-term deep-space mission. Scientists
would need to identify key markers that could help predict which
individuals might experience which types of sleep or mood problems.
Because many of the problems showed up fairly early in the Mars500
mission, Basner hopes that future crew selection could include a
similar but shorter simulation to find out who may be affected and
who won't.

One simple way to try and sync up crews on future space missions
or on the Martian surface would be to adjust the proportion of blue
light that astronauts see at different points of the day. The
retina has a natural pigment called melanopsin that is
sensitive to the blue wavelengths and provides a direct relay to
the hypothalamus, the primary pacemaker for circadian systems in
the brain. Increasing blue light increases activity while increased
red light promotes sleep.

In 2015, the International Space Station will upgrade from its
stark fluorescent lighting to LED lights that can adjust their blue
wavelengths, which will provide astronauts with external cues to
regulate their sleep. Controlling lighting could be particularly
important on future Mars missions that stay for long periods on the
surface, because the Martian day is slightly longer than the one on
Earth.

As a final takeaway, the study could help individuals who are
not going into space. "It underscores the fact that people living
on Earth should get a chance to sleep more. It lets us improve
cognitively," said Basner.